Piezo-electric crystal-controlled oscillation generator



June 3, 1930. H. EBERHARD 1,761,332

PIEZO ELECTRIC CRYSTAL CONTROLLED OSCILLATION GENERATOR v Filed Oct. 27, 1927 lawn/0r.-

Patented June 3, 1930 QNITED STATES HEINRICH EBERIEAR D, OF BERLIN, GERllIANY PIEZO-ELECTRIG CBYSTA'L CONTROLLED OSGILLATION GENERATOR Application filed October 27, 1927, Serial No. 229,102, and in Germany October 28, 1928.

An application for this invention filed in GermanyOctober 26, 1926. My invention relates to a device for generating electrical oscillations by means of piezo 5 electrical crystals such as quartz.

It is a known fact that a piezo electrical crystal acts in stabilizing the'frequency of an electrical oscillation generated by a 3 electrode valve. Nevertheless all connections used until now for such purposes areas far as I am aware such as to generate oscillations also if a piezo electrical crystal would be absent, the electrodes surrounding said crystal being able to work as a condenser. Such connections have the draw-back that oscillations may be generated corresponding to quite another frequency than the natural frequency of the crystal. In such a connectionthe piezo electrical crystal does not in any case work as a frequency stabilizing device;

4 My invention is able to avoid such drawbacks. I found by means of experiments an extremely simple connection for producing oscillations by means of a 3 electrode valve and a piezo electrical crystal, effective both for enerating long and very short waves.

y invention may be best understood with reference to the accompanying drawing, 'fy

showing by means-of examples connections for producing oscillations according to my invention.

1 is anamplifier valve of usual construction with filament 2, actin as cathode, grid ament battery, 6

3 and anode 4. 5 is the as the plate voltage, 7 and 8- two parts of one coil. The part 8 has-however, a muchvhigher self-induction than the coil 7, so as to work as an impedance 0011. A quartz c stal, for

instance of the shape of a disc place between 40 two plates, is illustrated by 9. Experiments have shown that the arrangement above described oscillates particularly easily and effectively if the natural oscillation of the coil 7 is somewhat approximate to the natural oscillation of the quartz resonator. 9. It has been observed that with this connection the self-excitation of the valve is eflected both by quartz c stals for long waves with theuse of suitab e coils 7 and 8 and particularly well by quartz crystals of very high natural frequency. With the arrangement shown in the drawing I am indeed able to excite such high frequencies that the wave-length appertaining to such oscillations amounts to only a few metres. v

The device according to my invention may be used, both as measuring-instrument and 1 for the separate control of transmitters, genof the up or coil art 7, to connect a small variable p ate con enser 11 parallel to coil 7,

as shown in Fig. 2. Y

The tube 1, connected according to my invention, does not operate properly as a gencrating tube but as an amplifier valve, amplimg the iezo electrical oscillations of the quartz. 'lliese oscillations are brought up to a considerable amplitude by means of the oscillating arrangement of the coil of 0scillating circuit) connecte to the crystal and the anode of the amplifier. 12 indicates a high ohmic resistance connected to battery 13, by means of which the grid may be brought to a suitable --voltage.

I claim:

1. In an arrangement for producing electrical oscillations an amplifying valve, an oscillating device connected to the anode of the amplifying valve on one side and a piezo electrical crystal on the other side, said crystal being arranged between said oscillating device, and the grid of the amplifying tube, and an inductance connected to said oscillating device and the piezo electrical crystal on one side and to the filament of such an amplifying device on the other hand.

2. In an arrangement for producing electrical oscillations an amplifying valve with at least three electrodes, a piezo electrical crystal connected tothe grid of said amplify- -ing valve, one of its natural frequencies be ing equal to the frequency to be generated by the arrangement, a coil connected to said crystal, and the anode of the amplifying device, said coil being nearly tuned to the frequency to be generated, and another coil connected to the crystal and the filament of the amplitying devlce this coil having a greater selfinductance than the former coil.

3. In an, arrangement according to claim 7 2 a. condenser connected to the ends of the firstly cited coil.

4. In an arrangement for generating electrical oscillations an ampli ing tube with at least three electrodes, a coil eing connected with one end to the anode and with its other end to the filament of said amplifier, two electrodes connected to the grid of said amplifier and to one inner point of said coil, and a piezo electrical crystal mounted'between said two electrodes.

5. In an arrangement according to claim 4 means for varying the point on which the electrodes of the crystal are connected to the self-inductive coil, the'crystal being removabglmounted between said electrodes.

. testimony whereof I have aflixed my to signature. 7 a

HEINRICH EBERHARD. 

